Global options are global in the sense that they apply to every command
invocation regardless of action to be performed. They include authentication
credentials and API version selection. Most global options have a corresponding
environment variable that may also be used to set the value. If both are
present, the command-line option takes priority. The environment variable
names are derived from the option name by dropping the leading dashes (--),
converting each embedded dash (-) to an underscore (_), and converting
to upper case.

For example, the default value of --os-username can be set by defining
the environment variable OS_USERNAME.

Commands consist of an object described by one or more words followed by
an action. Commands that require two objects have the primary object ahead
of the action and the secondary object after the action. Any positional
arguments identifying the objects shall appear in the same order as the
objects. In badly formed English it is expressed as “(Take) object1
(and perform) action (using) object2 (to it).”

Each command may have its own set of options distinct from the global options.
They follow the same style as the global options and always appear between
the command and any positional arguments the command requires.

The objects consist of one or more words to compose a unique name.
Occasionally when multiple APIs have a common name with common
overlapping purposes there will be options to select which object to use, or
the API resources will be merged, as in the quota object that has options
referring to both Compute and Volume quotas.

network: (Compute, Network) - a virtual network for connecting servers and other resources

networkagent: (Network) - A network agent is an agent that handles various tasks used to implement virtual networks

networkautoallocatedtopology: (Network) - an auto-allocated topology for a project

networkflavor: (Network) - allows the user to choose the type of service by a set of advertised service capabilities (e.g., LOADBALANCER, FWAAS, L3, VPN, etc) rather than by a provider type or named vendor

The actions used by OpenStackClient are defined below to provide a consistent
meaning to each action. Many of them have logical opposite actions.
Those actions with an opposite action are noted in parens if applicable.

authorize - authorize a token (used in OAuth)

add (remove) - add some object to a container object; the command
is built in the order of containeraddobject<container><object>,
the positional arguments appear in the same order

The command structure is designed to support seamless addition of plugin
command modules via setuptools entry points. The plugin commands must
be subclasses of Cliff’s command.Command object. See Plugins for
more information.

Commands are added to the client using setuptools entry points in setup.cfg.
There is a single common group openstack.cli for commands that are not versioned,
and a group for each combination of OpenStack API and version that is
supported. For example, to support Identity API v3 there is a group called
openstack.identity.v3 that contains the individual commands. The command
entry points have the form:

action_object=fully.qualified.module.vXX.object:ActionObject

For example, the listuser command for the Identity API is identified in
setup.cfg with: